1.a.b.c.d. The pun doesn't translate, as in Italian 'scala' means both 'stair' and 'musical scale'

Whereas a translation is presented as 'singable', it's by no means intended to be a literal version of the lyrics in another language. It just aspires to be a rhythmical, sometimes also rhyming, rendition of the text, so that different words can be sung along to the music, keeping the original meaning as much as the syllable count makes it possible .